Effect of trade on global aquatic food consumption patterns

The study addresses how international trade influences global patterns of aquatic food consumption and the human aquatic food trophic level (HATL). Aquatic foods are central to achieving food security and nutrition goals, yet climate change, overfishing, pollution, and urbanization challenge supply. Production from fisheries and aquaculture has grown substantially, and aquatic foods are among the most globalized food commodities. However, a key knowledge gap persists due to mismatches between species-level production data and product-level trade data, as well as processing weight changes, limiting understanding of consumption patterns and trade impacts compared to land-based food systems. Trophic level is used widely in ecology and correlates with product value, but its relationship with nutrient content or contaminant risk is not straightforward. The paper aims to quantify HATL and evaluate how trade affects both availability and trophic composition of aquatic foods across 174 countries from 1976–2019.

Prior work documents rapid growth and globalization of aquatic food production and trade and highlights their importance for food security and sustainable development. Evidence on trade’s impacts on food security is mixed: some studies find benefits for access and nutrition, while others highlight potential negative effects on vulnerable communities. Compared to agricultural trade, reconciling aquatic production and trade data is harder due to species vs. product reporting and processing losses. Trophic level has been employed as a composite ecological and value indicator, with higher trophic levels generally fetching higher prices, but nutrient density and contaminant accumulation do not consistently align with trophic level. Existing studies have analyzed regional trade networks and consumption, but a global, species-level assessment linking production, trade, and consumption to HATL has been lacking; this work fills that gap by integrating FAO data with trophic information from FishBase and a mass-balance reconciliation approach.

Data sources: The authors used FAO FishStatJ time series for aquaculture, capture fisheries, and trade, harmonized for 174 countries from 1976–2019. They removed items totaling less than 100 t over the entire period to aid conversion and trophic assignment (affecting ≤0.044% of volumes). Scope: Aquatic foods include freshwater and marine fish, cephalopods, and crustaceans; mollusks, aquatic plants, algae, echinoderms, cnidarians, other miscellaneous aquatic animals, inedible items, fishmeal, fish oil, and processed products without conversion factors were excluded. Engraulis ringens was excluded from capture due to dominant reduction use and lack of reliable consumption shares. Live weight conversion: Trade commodities reported by species/species groups and processing methods (fresh, frozen, dried, fillets, etc.) were back-converted to live weight using preprocessing and preservation factors from published sources. Missing method labels were assumed fresh/whole. Post-conversion, global imports to exports averaged 0.99 ± 0.04:1, supporting conversion reliability. Trophic level assignment: Species-level trophic levels were obtained from FishBase. For species groups (e.g., “Groupers nei”), all economically relevant species matching common names and country fishing areas were identified and averaged. Unidentified categories (e.g., Freshwater/Marine fish nei) were assigned production-weighted average trophic levels from identified items within the same area and country, or regionally if needed. For generic trade groups (e.g., Tunas nei), trophic levels were weighted by global production of included species, prioritizing the most productive when lists were long. Fixed trophic levels were assigned to broad groups where necessary (Crustaceans 2.5, Cephalopods 3.0, Demersal percomorphs nei 4.0). Temporal and spatial variation in farmed species’ effective trophic level (feed-based) was not modeled. Human Aquatic Food Trophic Level (HATL): HATL was computed annually by country as the live-weight–weighted average trophic level of species/groups in apparent consumption: HATL = sum(TL_i * W_i)/sum(W_i), similarly applied to aquaculture, capture, imports, and exports. Species-level mass balance: A four-step reconciliation subtracted reexports from imports and exports from the combined pool of domestic production plus remaining imports at species/group level. Matching proceeded from exact commodity names to generic categories (e.g., species-to-group and group-to-species), then to “nei” categories, proportionally deducting matched exports. This yielded final apparent consumption by commodity and country. Resulting reconstructed exports captured 95.3 ± 0.9% of original exports, with export-to-import live weight ratio 0.96 ± 0.03:1; remaining unmatched exports accounted for 1.1 ± 0.4% of total consumption. Validation and comparisons: The authors compared balanced per capita consumption to FAO Food Balance Sheets; 66.7% of countries differed by less than 20% on average, 73.6% by less than 30%, attributing residuals to non-food uses, stock changes, and conversion factor differences.

• Global per capita consumption of aquatic foods rose markedly from 1976 to 2019, while HATL declined from 3.42 to 3.18, opposite to broader human trophic level trends that include terrestrial foods.
• The decline in HATL is primarily driven by rapid growth of low-trophic-level aquaculture relative to largely stagnant capture fisheries. Aquaculture trophic level is on average ~0.8 lower than capture fisheries. Aquaculture’s share of aquatic foods rose from about 6% in the 1960s to 56% in 2020.
• Regional patterns vary: Asia’s per capita consumption increased rapidly (strongly influenced by China) while HATL fell by ~0.08 per decade (about 1.4× the global rate). Europe and South America saw rising then declining per capita consumption since the 1990s, with increasing HATL. North America’s consumption rose slightly while HATL declined. Oceania uniquely experienced increases in both consumption and HATL over the long term.
• Current status: Asia has the lowest HATL; Africa has the lowest per capita consumption and a low HATL; Europe and Oceania show the highest per capita consumption and HATL.
• Trade grew across all continents, with Asia and Europe as major hubs; post-1995 (WTO era), Asia and South America generally have trade surpluses, Africa and North America deficits. Some countries dominate volumes (e.g., China, USA, Norway, Thailand, Japan).
• Trophic levels of traded products are generally high (continental trade TL >3.3; most countries’ median import/export TL >3). Asia and South America now import higher-TL products than they export, while North America and Europe show the opposite; Africa’s import volumes are growing faster than exports. Global import TL stayed roughly 3.5–3.6 as both high-TL (e.g., salmonids) and low-TL (e.g., tilapia, shrimp) trade expanded.
• Trade effects: After accounting for trade, per capita consumption decreased in Asia and especially South America (consistent with their export orientation) but increased or was maintained elsewhere; HATL remained nearly unchanged continentally in Asia and South America, declined in Oceania post-trade due to exporting higher-TL species and importing lower-TL species, and mildly declined in North America and Europe in recent years. Africa is the only region where both post-trade per capita consumption and HATL increased, underscoring trade’s role in improving availability.
• Nationally, more than 60% of countries experienced increases in availability and HATL due to trade; over 70% of countries in Africa and Europe benefited on both dimensions. The USA’s import share of consumption rose from about one-third (1961) to nearly three-quarters (2019).
• Trade reduced global heterogeneity in HATL, particularly in Europe, North America, and Africa, and increased mean HATL in most continents, indicating a harmonizing effect of international trade on aquatic food consumption patterns.

The study demonstrates that international trade has been pivotal in shaping global aquatic food consumption by increasing availability and elevating the trophic composition of consumed species for most countries, thereby reducing geographic disparities in HATL. Although global per capita consumption rose, HATL declined due to the expansion of low-trophic-level aquaculture, especially in Asia, indicating a structural shift in supply. This shift can support sustainability objectives by reducing reliance on marine ingredients and enabling lower environmental footprints relative to many terrestrial animal-source foods. Yet, the benefits of trade may accrue disproportionately to higher-income consumers, as traded products often comprise high-value, high-trophic-level species. Consequently, policy measures ensuring fair, transparent, and inclusive trade are needed to extend benefits to vulnerable populations. The harmonization of HATL across countries suggests that trade helps smooth regional imbalances in production capacity and demand, contributing to food security in regions like Africa where demand growth has outpaced supply. Nonetheless, differential dietary preferences, affordability, and domestic supply chain constraints can limit direct gains for all groups. Overall, the findings support the view that trade is an important mechanism for achieving more equitable and sustainable aquatic food distribution, while highlighting the need for policies addressing remaining inequalities and ensuring environmental sustainability of production.

By constructing species-level mass balance and trophic-level datasets for 174 countries from 1976–2019, the paper quantifies, for the first time at global scale, how trade influences aquatic food availability and dietary trophic patterns. Key contributions include: documenting rising per capita consumption alongside declining HATL driven by aquaculture growth; showing that trade increased availability and HATL in most countries (>60%) and reduced cross-country HATL disparities; and identifying changing regional trade structures (e.g., Asia and South America exporting more low-trophic products while importing higher-trophic ones). These insights broaden the focus from productivity and economic outputs toward equitable distribution of aquatic foods. Future research should: integrate finer-resolution data on food loss and waste, non-food uses, and stock changes; incorporate effective trophic levels for farmed species based on feed; improve and localize live-weight conversion factors; and assess the distributional and nutritional impacts of trade on vulnerable populations. Policy efforts should aim to create fair and adaptive trade environments that enhance access and affordability while safeguarding environmental sustainability.

Data and methodological constraints include: potential inconsistencies in production and trade statistics across countries; differences relative to FAO Food Balance Sheets due to treatment of non-food uses, stock variations, and conversion factors (with two-thirds of countries within 20% difference and most within 30%); inability to fully remove effects of species used for reduction (beyond Engraulis ringens) and other non-food uses; unaccounted food loss and waste and other supply chain leakages that may diminish realized consumption gains; assumption of constant trophic levels across space and time and omission of effective (feed-based) trophic levels for farmed species; and possible temporal/geographic variation in live-weight conversion factors. These limitations imply that estimated gains reflect potential availability rather than actual intake, and that some national estimates may be over- or under-stated.